Internally fired gas burner with radiant end wall



Nov. 20, 1951 A'. A. FuRczYK 2,575,514

INTERNALLY FIRED GAS BURNER WITH RADIAN'FEND WALL Filed July 5l, 1946 f ff @5.57 ya f .15

IN V EN TOR.

Patented Nov. 20, 1951 INTERNALLYFIRED GASBURNElk-WITH RADIANT ENDWALL".

Alfons A. Fuc'z'yk; Philadelphia," Peil', as'si'gnr t Selas Corporation of America," Philadelphia, Pa'fa corprat'ion ofA Pennsylvania- Application-July1.51946,'SerialfNo. '6873263 6 y"Cla'iis (Cl. 15'8i-99)4 My `ininentirl relates to burners,'and 'more vpartiularlto burners' 'of the 'type'having" a"sub`=` stantia'lly' closed' combustion" space' in which practically complete comb'stir'i'bf a combustible" gaseous mixture 'is accomplisned'and "fromwhicn heated -pipdiicts "of combustion are discharged atfa relatively '.hig'hvelocity throught a'res'tri'cted outlet in the for'r'irof a high' "temperature" gasv stream.'

It is 1an object of'ithe'invention'to 'provide an improvement in burnersbf this typeparticulafly t6 'obtain better use'of the" highte'mp'erature heat" inggases produced by the'bur'ner." I accomplish' this' by providing ahouw'refractory body rdrmjing 'the' combustionspace whos'erestricted outlet er'id is' formed in 'such a-m'a'nner'that workduririgv its" movement past suchlbutl'etend at close range thereto 'is' firstv heatedA primarily 'by radiant heat from a refractory wall heated'tc incandescen'ce by the" high temperature gasesA andV `while 'the work is out of 'physical contact With'tl'ie 'pririary/ high velocity 'gas fstream'; and the workther'e#A after is immediatelyheated to a higher 'teme perature by moving 'directly iritoA the `primary 'high'- velocity gasI stream. D a

The refractory Wall pastY whicli the` work initially moves 'and the' 'restricted outlet throughr which the prir'naryhigh temperature'gas 'stream-V` issuesyare preferabiyembodiedinf a single re'- fractory Ashape or insert 'gied to the 'outlet' Aend of the hollow refractory body.v Such refractory shapev is relatively small? 'comparedftd the size' maier-heating oftheworkby radiantheatf' The"`above" and other objects and advantages of "the invention lwill bemor'e fully 'iunder's'tod' upon`^reference "to the' "following f' description and:

accompanying drawin'gfor'min'g' ajpari'of this spe-cimenta and pfwhjie'hrie.' i isfgfverticar sectioned viewy taken atl une Ii-I of Fig: 2, ora

Fig. 4 is -an end .view of a modified frnifof tip` fthe '-burner" illustrated Fig. 1; "and "Figi 5 ringlshaped bas'e 'member' I I.' Aformed to' A'provide' an'` inlet' 'chamber' 'I 2 vhaving".a 'tli'r'e'aded opening l' I4 wliichs adapted "to be connected to "asuitf able source of supplyA of a combustible gaseous" mixture. The' 'base'.m'ember" II "is" .fdr'mediwith an 'inwardly"'extedigshouldr 5 at the'A top part bf 'the inlet- 'chamber' I2 "treceive `the"lower y" flanged "e'd I 6 'of'a circular burner" 'screenM I1 i having 'a plurality 'of srnall apertiesl extending" therethrough.'h 4 At the toplface'bftlebase member'l Ij isise'curedNl a 'ring-shaped "clamping "'plate "I 9," as "by 'screws zuffor exemplaire' inneredg Aof' which weriisz`- screen -II 'and extends' .abve 'the 'top,surface` of""" the latter to form a 'short passage 21 lvat the 'inlet' end-of the conibustion space"24`.i

Abt the hllOW bdy 2 6 iS diSpOSedlthe `10W`er"` end of a hollow cylindrical-member A28 which bears" against the clamping? plate' I9 rland "extends .up' wardly therefrom alongside of 'the metal' shell ZZ'to the sloping.oritaperediupper end-'ofthe'"g Shel-l1 Within'the member .28'and forming there: witlr a part of "the refractory` wall of"`fthesp'ace 24 fis' disposed a' hollow' "cylindrical member "29":x The lower end of the member .29 bears againsttlie topsurface of thehollow.' member 26, andtle'f upper end thereof bears' 'against' 'the larger end offan annular member l30 which fori'n's the 'die-"l charge 'or outlet'end of the 'combustion''spac'eZILiy The annular member 30,"whichprojects through the small vopen end of the outer shell"22;` bears' against 'the sloping for' tapered' part vof Lthe shell n and lat the 'eXtreme 'upper fend is'fiXed' an' insert* or' tipl3I'` as'willbe described'more' fully herein? after, having' 'an elngatedfnarrow vr'slot kforming' the restictedoutlet 25"for`tl1`e ccmbi'i'sticin space ZI'I` In order to withstand the high temperatures produced in the combustion space 24 during operation of the burner, the hollow member 26, inner cylindrical member 29 and upper annular member 3D may be formed of a suitable refractory material, such as silicon carbide, for example, having high resistance to thermal shock and possessing rigidity and strength at high temperatures. The outer cylindrical member 28 is preferably formed of a refractory material, such as mullite, for example, possessing good insulating properties and having adequate strength' to serve as the outer portion ci the refractory wall. Although not to be limited thereto, the burner screen I1 may be formed of a refractory material, such as aluminum oxide, for example.

The refractory Wall parts justV described may be secured to one another and Within the outer shell 22 by a suitable high temperature air-hardening cement, as indicated at 32, 33, 34 and 35, respectively. Such a high temperature cement upon hardening provides a rigid and unitary burner structure in which all of the refractory Wall parts are eifectively united to form the combustion space 24.

To operate the burner III to produce a high velocity gas stream of heated products of combustion, a combustible fuel mixture comprising a gaseous fuel and a combustion supporting gas is supplied through the inlet I4 from a suitable source of supply. When the burner IG is relatively cool and at a low temperature, the gaseous mixture supplied thereto passes through the inlet chamber I2, burner screen Il and space 2li from which it is discharged through the restricted outlet 25. The combustible gaseous mixture is initially supplied to the burner III at a relatively low pressure which may be equivalent to a pressure corresponding to about 5 or 6 inches of Water column, for example, so that the gaseous mixture discharged from the space 24 can be ignited to produce and maintain a flame at the outlet 25.

When a flame is being maintained at the outlet 25, the pressure of the gaseous mixture supplied to the burner IIl may be momentarily reduced suinciently to cause the iiame to backfire through the outlet 25 onto the burner screen II in space 24. When this occurs a plurality of flames are produced and maintained at the upper ends of the small apertures I8.

When the flames are being maintained Within the space 24 at the top surface of the burner screen I1, the pressure of the gaseous mixture supplied to the burner I0 may then be increased. After a short interval of time theflames maintained at the top surface of the burner screen I'! effect such heating of the inner refractory lining that these surfaces are heated to a high incandescent temperature. The heating 'of the inner refractory lining to a highly incandescent condition and radiant heat therefrom promotes substantially complete combustion of the gaseous mixture in the combustionspace 24 before the mixture reaches the outlet 25. From the outlet 25 is discharged a high velocity jet or stream of heated gases at a temperature nearly equal to the temperature in the combustion space 24 and consisting substantially entirely of heated products of combustion.

During normal operation the burner IIl is characterized by the absence of a bright and lumin-ous name. It is only when the burner is iirst started that a flame is momentarily maintained at the elongated slot or outlet 25, as previously explained. After the gaseous mixture has. 011.9@

been ignited, the delivery pressure of the mixture is reduced suiiiciently to cause baclniring into the combustion space 24, so that burning of the gaseous mixture will be initiated at the top surface of the burner screen il.

In a burner of the type just described, the heated products of combustion are discharged from the combustion space 24 through the restricted outlet 25 at an elevated temperature ranging from 2700 F. to 2900 F. and higher when a combustible gaseous mixture of air and ordinary gas, such as city gas having a b. t. u. rating of about 550 b. t. u. per cubic foot, for example, is supplied at a pressure in the neighborhood of three pounds per square inch. Under such operating conditions the pressure in the combustion space 24 may be equivalent to a pressure corresponding from to 70 inches of Water column and appreciably above that of atmospheric pressure. 'I'he heated gases are discharged from the burner at an average velocity of about 750 feet or more per second and at a maximum Velocity of about .1.000 feet or more per second.

In many heating applications it has been the practice to employ burners of the type herein described to eiect heating of Work entirely by the high temperature gas stream into which the Work is adapted to pass at a region closely adjacent .to the restricted outlet. In other Words, the Work is heated from the ambient temperature to the desired elevated temperature entirely by the high temperature gas stream.

In certain heating applications, heating of the Work entirely by the gas stream does not utilize the high temperature gases efciently. This is particularly true when Work of elongated extent is moved into the gas stream at a region closely adjacent to the restricted outlet. This is so because the portion of the gas stream, through which successive longitudinal portions of elongated Work initially pass, is only utilized to heat the Work to an intermediate temperature short of the final temperature to which the Work. is ultimately heated by the portion of the gas stream into which the work subsequently passes. Stated another Way, all parts of the gas stream are at a high temperature capable of heating successive longitudinal portions of the Work to the desired elevated temperature, but only the part of the gas stream into which the work passes after being initially heated is effectively utilized in this manner.

In accordance with the invention, in order to obtain better use of the high temperature products of combustion formed in the combustion space 24, these heated gases are utilized to heat to incandescence 'a refractory Wall 36 which is adjacent to the restricted outlet 25 and over which the work is adapted to move before passing into the gas stream issuing from the restricted outlet. The Work passing over the refractory wall 36 at close range thereto is eii'ectively preheated by radiant heat therefrom to,

bring successive portions of the work to an intermediate temperature short of the final high temperature to which the Work is ultimately heated. By preheating work in this manner, successive portions of the work are heated to the desired iinal elevated temperature in the gas stream in a Shorter interval of time'while being impinged by the high temperature Aheated products of combustion.

To heat the refractory wall 36 to as high an incandescent temperature as possible and eifect optimum radiant heating of Work before passing` Byfproviding:thezrecesses 31 lwhichY are ,considi-` erably*largerf-in"y cross-sectional area than the` passages A33, therheatedxgases 1 emerging frornzthe passages into: the recessesgimmediately; expandN laterally, whereby'thevelocityfof:theigases passingzfronnthexopen ends of the recesses is. slowed down considerably. The passagesff-Sfxare'quite-r smallandf-onlydivert ai sufficient quantity of heatedproductsof combustion to insure :heating thef'inner': wall surfaces of", therecesses'v 31 to a high -Yincandescent temperature.

By; heating` the inner Awall surfaces of the '-recessesf31'to incandescence'linwthe manner just'.

described; efficient' radiant` heating Aof work is effected: when: .the `work passes-'over' the recesses at closef range ytofthe refractory Wall 36, inthe manner indicated -atB! in Fig. 5: After'the work is.preheated byjradiant heat from the refractory wall:4 36 ,c successive longitudinal portions -of the work pass directly into the primary gas stream issuingjrom: the restricted outlet 25Ato heat .the worktovthe desiredfnal high temperature.

In certainrinstances the final elevated temperature to which the work is 'heated may be the fusing temperature 'of the work, aswhen a glass fila-- mentor rod isr fed'into thefhigh temperature gas stream, forexample.' In heating applications of this kind, the interval of time in which-.successive longitudinal portions V`of the Work must be irnpinged by the heated products of combustion, to bring the workitofazfusingftemperature, is materiallyshortened by .preheatinglthe.workfwith the aid of the refractory wall 35 at the outlet end of the hollow refractory body.

It Will now 'be understoodV that the work moving toward the primary gas stream produced at thefrestrictedoutlet `22": is .first heated primarily by ,radiante heat frornthe refractorylwall .3 6 While the work isffout of physicalcontact withthe :primary gasfstrearn. While the .heated products of combustion:u discharged Yfrom the recesses@ 31 envelop the work adjacent to thefrefractorywall 36, such gases are slowmovingA gases and are not relied upon to effect rapid 'convection heating of the work in the same manner as the high velocityprimary zgas stream; Moreover; only a-l relatively small quantity of heated products of combustion is diverted through the tiny passages 38 which is just sufficient to maintain the inner wall surfaces of the recesses 31 in a highly incandescent condition.

Since the heated products of combustion in the combustion space 24 are constantly rsweeping over the inner face of the refractory wall 36, such heated gases contribute to heating the entire mass of the wall 36 to an incandescent temperature. Therefore, heat is effectively conducted through the wall 36 to the entire surface area at the outer face of the wall 36 due to the continuous heating of the inner face thereof by the heated products of combustion sweeping over the wall. In addition, such heating of the inner face of the Wall 3E reduces the heat loss from the inner wall surfaces of the recesses 31, so that the latter will be maintained at a high incandescent temperature.

i perature.

InfFigs. 4andi5LI havefshcwna modirledfc'riny of 'burner tipi inr: whichi recesses 31m' are forinediI at 'thezinnerface rather than at" thef outer' fface of afrefractory Wall 36o; In such rri'odiiied forni? of' burner. tip," nop'assages forv diverting p'roducts' of combustion' extend from' the bottoms :of lthef recesses 3M. to the outerz'fa'cefof the"refrac-toryfv wall 36d'.` However; by providin'gtle multiplie;A ity of :recesses 31a'at the innerfaceof the refracLA tory'wall 33a Whit-hf are'of such depth that'a'rela-YV tively thin wall Ysection '4t is formed between the? bottoms oftherecesses 'and the outer facefof the' refractory wall 36a, such thin wall secti'on'canbe` readily heated-- to Aa high incandescent tem- This' is-so becausethe highrtemperatureheated'products of combustion in the 'come` bastion spacezl 2 i f aref diverted into the pockets'oif" cups frmediby the-recesses 31a to heat the inner? wall' surfaces' thereof' to incandescencei Since the overall inner wall surface `-areapresentedf tofthe heatedi products @of combustion-iis considerably greater than the exposed surf ace?.

neatV is'fcffectively conducted throughthe re`f-rac'y tory-wall'from'iit's inner'faceto theiouter face? Moreover; byforming'the refractory wall 36a`so that the thicknessesrsof thewalls betv've'en"adjaLv cent recesses are' :relatively small', heatfis'rapidly? conducted through th'ezV massof the" refractory f lwalifto' `the 2 thin .Twall'l 'section 48 at fwhichi region" heat is` concentrated'toimaintainlthe outer face? of the` tip at" ani extremely high"v incandescent" temperature'rtoproniotefradiant heati'rigl-of Yvs/"tirlrzl In: the ernbcdin'ient first described? and "als'oin ti'ieimodiiiedform ofFig'siif-andl, the refraci torywall. isf at` the extreme outer end-lof -th'e hollowrefractory body and contiguous to anddirectlyi' at'one side-of" the elongatedv restricted voutlet 25, wherebythe highest temperature heatedfprod uct-sof cc'nmbustion about to issue from the combustion space A2111 are effectively utili'zed'to 'heatthe refractor-ywalls 33e-nd 36ato incandescen'cel" and then immediately pass through the restricted" outlet Ein a path of flow-characterized by the absence 0f any barriers or flow impediment Walls*v tending to`l reduce'- the velocity at which@ thfe heated'gases-discharge fronithe burner'tip.- Inf' this way newly vrformed heated products -vof vcom:J e bustion are continuously flow-ing freely and? sweeping over the inner faces lof theref-ractory"` walls and "33d, before rentering the-restricted* outlet 25,5' to maintain theou'ter faces thereoflat" ahighincandescent temperature.`

In order Vtofacilitate the fabrication"offburners' of- -the 'kind-f described` and'Y embodying the inven-L f tion, the refractory walls 36 and 33a and restricted outlets 25 adjacent thereto are embodied in relatively small refractory shapes which are U-shaped in section and may be referred to as tips or inserts for the burners. As best shown in Figs. 2 and 4, the lindependent tip units 3| and Sla are octagonal-shaped and the longer side walls thereof formed with outwardly extending shoulders lil. The annular member 33 of the hollow refractory body is formed with recesses e2 to receive the shoulders 4| and the tips 3| and 3 l a may be securely xed in position in the annular member 33 in any suitable manner, as by a suitable high temperature air-hardening cement, for example. This produces an linexpensive and easily manufactured construction and provides a burner tip of the type described and illustrated which possesses exceptional strength.

It is desirable to form a burner tip like the independent tip units 3| and 3|a of a refractory material, such as beryllium oxide, for example, because such material can withstand exceptiom :ally high temperatures and possesses good heat conductive properties. Since refractory materials like beryllium oxide are relatively expensive, 4it is desirable to reduce the quantity of such material employed to provide the hollow refractory body. This is made possible by providing -the tips`3l and 31a which are relatively small :and inserting such tips into the larger annular `member 30 which may be formed of less expensive refractory material, such as silicon carbide, for example.

Although I have illustrated and described particular embodiments of my invention, I do not desire to be limited to the particular arrangements set forth, and I intend in the following claims to cover all modications which do not depart from the spirit and scope of the invention.

What is claimed is:

1. A gas burner for heating work comprising structure including a hollow body which provides a substantially closed combustion space having an inlet through which fuel to be burned in said space is introduced and a restricted outlet through which products of combustion are exhausted, said space having its inner wall surface and outlet composed substantially entirely of high temperature refractory material, the end of said body adjoining said restricted outlet including a thin refractory wall forming on its outer portion an exposed surface, said Wall at a face thereof having a plurality of spaced apart recesses, said recesses being formed at the outer face of said wall, and tiny passages formed in the latter for diverting products of combustion from said space into said recesses.

2. A gas burner for heating work comprising structure including a hollow body which provides a. substantially closed combustion space having an inlet through which fuel to be burned in said space is introduced and a restricted outlet through which products of combustion are exhausted, Said space having its inner Wall surface and outlet composed substantially entirely of high temperature refractory material, the end of said body adjoining said restricted outlet including a thin refractory wall forming on its 4outer portion an exposed surface, said wall at a face thereof having a Aplurality of spaced apart recesses, said recesses being formed with substantially straight Walls normal to and extending inwardly from the outer face of said refractory wall, and tiny passages formed in said Wall for diverting products of combustion from said space into said recesses,

tion are exhausted, an insert to be placed in said restricted outlet being made of material having high heat conductivity, said insert being substantially cup-shaped and having an opening in the bottom adjacent to one side thereof through which the products of combustion pass, the remainder of the bottom being of substantially uniform thickness.

4. A gas burner for heating work comprising structure forming a combustion chamber having an inlet for fuel and a restricted outlet through which products of combustion are exhausted, a refractory tip member made of material having a high heat conductivity located in said outlet, said tip being provided with an elongated opening adjacent to one edge thereof and having on its exterior a at surface extending from said opening toward the other edge thereof, said member being of substantially uniform thickness throughout the area thereof covered by said surface,

5. The combination of claim 4 in which theY surface of said tip is provided with a plurality 0f recesses extending from its exterior face toward the interior thereof.

6. The combination of claim 4 in which said tip is provided with a plurality of recesses extending from the interior thereof toward the outer surface.

ALFONS A. FURCZYK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,302,819 Lucke May 6, 1919 1,689,551 Hammond Oct. 30, 1928 1,704,875 Vaughn Mar. 12, 1929 1,912,612 Wills June 6, 1933 2,215,079 Hess Sept. 17, 1940 2,367,119 Hess Jan. 9, 1945 FOREIGN PATENTS Number Country Date 817,071 France May 15, 1937 

